"Pledge This!" isn't Paris Hilton's first acting gig — who can forget her smothered in hot paraffin in this year's remake of "House of Wax"? — but it somehow still seems odd for the socialite-cum-überceleb to get top billing in the film. ("Pledge This!" opens Friday.) Then again, musicians, athletes, standup comics and other miscellaneous famous folk try their hands at acting all the time.

Sometimes it's a smooth transition. Frank Sinatra's natural charisma easily translated to the screen and he even won an Academy Award for his performance as Maggio, the skinny private who never knew when to back down from a fight in "From Here to Eternity" (1953). Tom Waits has proven as distinctive an actor as he is a musician. Dwayne "The Rock" Johnson has switched easily from performing in the ring to big-budget action flicks. Even Senator Fred Thompson missed a few votes on the floor in order to act in dozens of films and television shows, including "Die Hard 2," "Cape Fear" and, of course, "Law & Order."

But sometimes non-acting celebrities find out that speaking lines and moving around at the same time isn't as easy as it looks. Herewith, some of the more awkward screen performances by non-actors through the years.

MICHAEL JORDAN in anything

In addition to Jordan's seemingly superhuman abilities on the court, he is immensely likable and not a bad-looking Joe. So how come in every single one of the movies, TV shows and the 20,000 or so commercials he's done, Jordan is as stiff and uncomfortable as a 10-year-old in a suit? Jordan's never had to play anyone other than himself, and yet he always comes off as profoundly wooden. Even Tweety Bird out-acted Jordan in "Space Jam" (1996).

JAY LENO in "Collision Course" (1989)

The '80s were all about the action buddy movie, a genre that successfully paired Eddie Murphy and Nick Nolte in "48 Hrs." and Mel Gibson and Danny Glover in "Lethal Weapon," to name just two. So how could the brilliant matching of Jay Leno with Pat "Mr. Miyagi" Morita go wrong? Yes, that's a rhetorical question. Stand-up comic Leno has always seemed self-conscious (even when he was funny, long, long ago), and his forced "Tonight Show" smiles do little to counter that impression. But cast as a Detroit cop against Japanese investigator Morita, having to run and wield a gun in addition to cracking wise, Leno seems as lost as a prom queen at a comic book convention.

COLLEEN HASKELL in "The Animal" (2001)

Reality TV seems to be the ultimate realization of Andy Warhol's "15 minutes of fame" theory. Everyday schlubs are seen each week by millions of people and some have even been able to milk that fleeting fame a bit past the final elimination round. But when "Survivor" castoff Colleen Haskell played Rianna, Rob Schneider's animal-rights-activist love interest in "The Animal," critics struggled to find words to adequately capture her screen presence. "Cute" was the most charitable term used to describe her non-performance, intimating that her role could have been played by a life-sized teddy bear — and perhaps should have been.

And perhaps should have been.

SHAQUILLE O'NEAL in "Steel" (1997)

You can't blame Shaq for seeming a bit stiff in this superhero B-movie: The titular character clanks around in a full suit of homemade armor. Based on a character in the DC Comics Superman family, Steel is an inner-city avenger who uses state-of-the-art technology to battle corruption and crime. Ironclad heroes don't quite translate that well to live action, but Shaq plays it so uptight-straight that it feels as if he himself is made out of metal, too.

Kiss in "Kiss Meets the Phantom of the Park" (1978)

Don't get us wrong. We love Kiss. And as kids, we were psyched for this Hanna-Barbera-produced TV movie that posited the rockers as superheroes — but oh, that acting. Paul Stanley's Queens accent is as thick as his platform heels. Ace Frehley giggles and squawks like a parrot on 'ludes. Peter Criss' actual voice was replaced by professional cartoon voicer Norman Alden (Aquaman on "Super Friends"). Only comic book fan Gene Simmons struck the proper tone, thus saving (heavily made-up) face — which may be why he was the only member of the band to do more acting in the wake of this film. "Kiss Meets the Phantom of the Park" is disavowed by the band, but it's a "so bad it's good" classic (and just out on DVD!).

CINDY CRAWFORD in "Fair Game" (1995)

Many models have made a successful transition to acting — Grace Kelly, Lauren Hutton and Charlize Theron come immediately to mind. But while she was certainly one of the most successful models of the '80s and '90s, Cindy Crawford just couldn't cut it as a thespian. In her one major film role, Cindy plays an attorney who needs the protection of cop-on-the-edge Billy Baldwin (whom some would likewise dub a non-actor) when she's targeted by the KGB. (Yes, that KGB.) For a whole lot of moviegoers, however, Crawford's abysmal performance was irrelevant in light of the movie's only draw: the removal of her shirt.

BOB DYLAN in "Masked and Anonymous"(2003)

Unless you worship at the altar of Dylan the musician, it's hard to find anything redeeming in his mumbling, disjointed performance as a fallen star attempting a comeback. Co-written by Dylan with "Seinfeld" alum Larry Charles (who also directed), this is one of those vanity projects that could only have been greenlighted due to the legendary status of its creator — again, his status as a musician. Anyone who doesn't own a well-worn copy of "Freewheelin'..." is advised to avoid.

PATTY HEARST in "Cry Baby" (1990)

Ya gotta love John Waters, champion of the freaks, outcasts ... and newspaper heiresses kidnapped by obscure "revolutionaries" who were forced to rob banks at gunpoint. Seminal tabloid queen Hearst seemed like a deer in the headlights as the mother of bad girl Wanda (Traci Lords) in this musical ode to 1950s' juvenile delinquents. But her cardboard performance may well have been at Waters' direction, since he brought her back in three more movies.

ANNA NICOLE SMITH in everything

Really like shooting fish in a barrel, isn't it? The poor girl doesn't even seem convincing when she plays herself, let alone actual characters in bombs like "To the Limit" (1995). One has to wonder what her billionaire octogenarian husband thought of her dramatic abilities. On the other hand, she was 26 when they married; he was 89. Did it really matter to him if she could act?

All of this just goes to show that while we've become a culture that places the highest value on celebrity, we really don't have that much respect for the craft of acting. How else to explain William Hung being cast opposite Nicole Richie in yet another remake of "A Star is Born"?

OK, we made that one up. Things haven't gotten that bad — yet.

Check out everything we've got on "Pledge This!"

Visit Movies on MTV.com for Hollywood news, interviews, trailers and more.